Direction: It consists of two statements, one labelled as Stateme
Direction: It consists of two statements, one labelled as Statement (I) and the other as Statement (II). Examine these two statements carefully and select the answers to these items using the codes given below:
Statement (I): The total instantaneous power in a balanced three phase system is constant and does not change with the time.
Statement (II): The instantaneous power in each phase is constant and does not change with the time.
A. Both statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B. Both statement (I) and Statement (II) are individually true and Statement (II) is not the correct explanation of Statement (I)
C. Statement (I) is true but Statement (II) is false
D. Statement (I) is false but Statement (II) is true
Please scroll down to see the correct answer and solution guide.
Right Answer is: C
SOLUTION
Concept:
The total instantaneous power in a balance three phase system is given by
P = 3VpIp cos θ
Where Vp is the phase voltage
Ip is the phase current
From the above power expression, the total instantaneous power in a balanced three phase system is constant and does not change with the time.
The instantaneous power in each phase is not constant.
Therefore, Statement (I) is true but Statement (II) is false
Note:
In a balanced load, the average power in all the phases is same.